Newspapers and similar articles present unique and challenging problems insofar as feeding them at regular rates of delivery is concerned. At one extreme are large, bulky big city newspapers containing many sections as well as large quantities of loose, advertising inserts. At the other extreme are thin, 6 to 12 page tabloids and similar documents. Yet, a commercially successful metering hopper needs to be capable of handling both types of newspaper products at high speeds, and without jams or misfeeds. Time is always of the essence in the assembly and production of newspaper products; therefore, stoppage of the production line to clear a jammed hopper or address another feeding problem is particularly aggravating and inefficient, all of which contributes to the challenge of providing a metering hopper that can handle a wide range of thicknesses and sizes of newspaper products reliably and at high speeds.
My prior metering hoppers have operated on a bottom feed principle by which stacks of newspapers are loaded into the top of the hopper and fed one at a time out of the bottom of the hopper in a transverse direction. In certain of my prior metering hoppers, such as disclosed in U.S. Pat. Nos. 4,557,472 and 4,911,421, I used a reciprocating shuttle across the bottom of the stack to engage the lowermost newspaper and drive it a short distance forwardly into a pair of powered nip rollers which then gripped the newspaper and pulled it the rest of the way from the stack. A barrier or stop at the front of the hopper kept newspapers above the lowermost newspaper in the stack from feeding simultaneously with the lowermost paper, but without blocking or interfering with movement of the lowermost paper.
Broadly speaking, the separating stop in some of my prior hoppers operated on the principle of cooperating with the underlying feed shuttle to define a relatively narrow outlet slot through which each successive, lowermost newspaper could be ejected from the hopper. The slot was thick enough to allow passage therethrough of the lowermost newspaper, but was thin enough to prevent any additional newspapers from exiting with the lowermost paper. The thickness of the slot could be adjusted by adjusting the vertical position of the stop, thus making the hopper adaptable for newspapers of different thicknesses.
One problem with the ejecting slot concept is that newspapers have a tendency to vary in thickness throughout a production run, even though they theoretically all contain the same number of pages and inserts. Thus, it is difficult to find a perfect thickness for the slot that will permit it to accommodate the random occurrence of overly thick newspapers without having a slot that is simply too thick to prevent the second and third newspapers from also being fed along with the lowermost paper. Such variations in the thickness profile along the leading edge of the newspaper can occur for many reasons such as, for example, when the relatively slick advertising inserts and other loose materials within the inside of the newspaper become shifted around in the paper to a point where, in one paper they may be in line with the separating stop while in another paper they may be offset to one side of the stop and thus present a thinner profile at the exact point of separation by the stop. Furthermore, the hard fold line that presents the leading edge of each newspaper in the stack can sometimes roll up or "balloon" so that, instead of the desired regular profile at the front of the newspaper, the newspaper presents a thick, loose front profile that is considerably wider than the ejecting slot. When such a malformed paper cannot pass through the slot, the machine jams and the line shuts down until the jam can be cleared.
Sometimes the rolled front edge of the newspaper is created before the stack is ever placed in the hopper, and at other times it is created during the ejection stroke itself. Due to the slickness of the advertising inserts, there is a natural tendency for the loose newspapers to become disheveled during the considerable handling that occurs both before and during placement in the hopper. This can produce the rolled front edge. Even if the front edge is not in a rolled up condition at first, the inserts may be in such a location that when the feed stroke of the shuttle takes place, the outer section of the paper tends to slide forwardly instead of staying locked together with the inserts and the other sections. This causes the front edge to loosen and roll up, preventing passage of the paper through the metering slot.
In order to accommodate the sometimes rolled-up front edge of the newspapers, I have provided previous designs in which the separating stop at the front of the hopper is flexible rather than rigid. While the rigid stop blocks the enlarged newspaper from passing through the slot, a resilient stop is more forgiving and will allow problem papers to pass.
However, the accommodating nature of a resilient stop sometimes limits its effectiveness as a separator. There is a tendency for the stop to flex forwardly all the time and permit the front edges of the newspapers to become progressively stairstepped under the stop. This causes increased down pressure from the stop on the second and third newspapers such that the bottom newspaper has difficulty breaking free from the stack during the feed stroke. Consequently, it may encourage the feeding of doubles and triples, which is undesirable.
At the other extreme are very thin newspapers, such as tabloids and advertising pieces on the order of from 5 to 10 pages. The small number of pages in this type of product makes the products so thin that it is difficult to place the separating stop at exactly the right height to yield a perfectly dimensioned, thin slot. Although there is less tendency for these particular products to produce a rolled up front edge, the risk of feeding doubles and triples is much greater.
My prior U.S. Pat. No. 4,911,421 explains the discovery that forming a longitudinal ridge in the newspaper product as it is being separated from the bottom of the stack is very helpful. The ridge tends to lock in place loose advertising inserts and the like within the inside of the newspaper and provide a stiffening column within the body of the newspaper that can be pushed against by the feed shuttle as it ejects the paper. It also has the effect of creating side slopes in the ridge that angle down away from the next overhead paper so that friction between the two papers is reduced. Generally speaking, I have found that the narrower the ridge the better; however, having a narrow support rail under the bottom newspaper to create the ridge also reduces the degree of surface contact between the rail and the newspaper, thus decreasing the ability of the rail to grip the newspaper and feed it forwardly. When using a support rail, the metering or separating slot at the front of the hopper is defined between the separating stop and the stop edge of the rail so that the peak of the ridge passes through the slot during each feed stroke.
However, I have found that having the separating stop located directly above the narrow support rail in this manner tends to aggravate the problem of feeding doubles and triples in relatively thin products. Moreover, it does nothing to relieve the jamming problem that occurs when the leading edge rolls up on larger size newspapers.